Method for making a composite sealing joint strip

ABSTRACT

According to the invention, the element, especially such as a motor vehicle door module ( 2 ), ready to be fastened onto a frame or other surface, is characterized in that the element is provided with a composite sealing bead of defined shape and defined cross section, said composite sealing bead having at least one catching part suitable for cooperating with a surface or frame of said element ( 2 ), at least one elastic part ( 5 ) and at least one adhesive part ( 6 ).

The present invention relates to a method of manufacturing a compositesealing bead suitable for assembling a modular element, especially suchas a motor vehicle door module ready to be fastened onto a frame orother surface.

The current tendency, especially in the motor vehicle field, is, rightfrom the design and production of these “modular” elements, especiallyin the case of vehicle doors, to integrate, into these modular elements,additional functions that are normally fulfilled by the frame or theother surface, with which said element has to cooperate. The term“modular element” is also understood to mean either an internalfinishing panel, which is intended to furnish the vehicle's door and isvisible from inside the vehicle, or an intermediate sealing sheet placedbetween said finishing panel and the automobile door.

This has the purpose of making it easier to assemble the vehicle byreducing the number of assembling operations on an assembly line, itemsof equipment and/or accessories fastened to the modular element havingbeen mounted beforehand in a separate unit or workshop.

Thus, modular elements for a vehicle door are known, which generally arein the form of a furnishing cover and are suitable for cooperating withthe internal face of the vehicle's door so as, for example, to mask andprotect the door closure mechanisms and/or the mechanisms for moving theside windows within the door.

The modular element is generally fastened to a door element by screwing,or by fit-in means, and it is necessary, at the interface between themodular element and the door element, to interpose a seal so as toprotect the volume lying within said door from environmental attack(moisture, dust, vibration, etc.).

For this purpose, it is known to interpose at the interface, as seal, afoamed sealing bead of the type indicated in the document EP 0 930 323.

Although this foamed seal best fulfils its sealing function when thedoor element and the modular element cooperate with each otherperfectly, it sometimes happens that, despite optimum fastening betweenthe two facing elements, the seal is not compressed over its entireperimeter and that a breach is opened, creating a passage for possibleenvironmental attack. This situation generally arises from variations inthe dimensional manufacturing tolerances on the door element and/or themodular element, it being possible for these minimum tolerance values tooccur at the same time.

For the purpose of achieving the shortest possible assembly time forthese modular elements, it would seem to be desirable to preequip themwith sealing means online in a short time.

It is an objective of the present invention to provide a novel way ofpreparing modular elements provided with sealing means, which modularelements can be stored for a certain period, to be able to be mounteddirectly on a frame or another receiving surface, especially a doorelement, in a small number of operations. The sealing means must be aseffective as possible in order to ensure that there is a seal betweenthe modular element and the receiving surface facing it, whatever thephase in which the sealing means is mechanically stressed (compression,extension, shear).

This objective, together with others that will appear later, has beenachieved with a method of producing a sealing bead between a firstelement and a second element, characterized in that one element chosenfrom the first and second elements is provided with a composite sealingbead of defined shape and cross section, of a composite sealing beadhaving at least one catching part, suitable for cooperating with saidelement chosen from the first and second elements, at least one elasticpart and at least one adhesive part suitable for cooperating with theother element when the first and second elements are to be fittedtogether.

By manufacturing a composite sealing bead having an elastic partinterposed between an adhesive part and a catching part, this ensuresthat there is a perfect seal between the two elements. The adhesive partand the catching part always remaining fastened to their respectiveelement whatever the mode of deformation of the elastic part of saidcomposite sealing bead.

Furthermore, the composite construction of the sealing bead allows it tofulfill itself a certain number of additional functions, such ascontribution to the fastening of the two elements together,soundproofing and shock absorption, by adapting a specific portion ofthe bead.

In preferred embodiments, the invention may optionally have in additionone or more of the following arrangements:

-   -   the composite sealing bead is deposited beforehand in a transfer        mold before it is applied to either of the first and second        elements;    -   the composite sealing bead is deposited directly on either of        the first and second elements;    -   the composite sealing bead is deposited by at least one        extrusion step;    -   the composite sealing bead is formed by extruding a        one-component product;    -   the composite sealing bead is formed in an extrusion head by        reaction between at least two components brought separately into        said extrusion head;    -   the elastic part of the composite sealing bead has, on its        peripheral surface, a skin forming an impermeable covering;    -   the elastic part of the composite sealing bead is a foamed        material;    -   the elastic part is based on a thermoplastic elastomer or on a        polyurethane which may or may not be modified by an elastomer;    -   the elastic part represents at least 50% by volume of the        composite sealing bead;    -   the adhesive part of the composite sealing bead consists of a        repositionable thermally activatable, photoactivatable,        chemically activatable adhesive;    -   the adhesive part of the composite sealing bead consists of an        adhesive that has a permanent tack or is moisture-reactive,        protected by a peelable film;    -   the adhesive part is formed with the peelable film and is        deposited by transfer onto the elastic part of the composite        sealing bead during removal of said peelable film;    -   the adhesive part of the composite sealing bead consists of a        hot-melt adhesive or is formed from a liquid adhesive or an        adhesive in a liquid vehicle;    -   the adhesive part of the composite sealing bead consists of a        sprayable adhesive;    -   the adhesive part and the elastic part of the composite sealing        bead are formed from an identical product;    -   the catching part of the composite sealing bead consists of an        adhesive part;    -   the adhesive part is coextruded with the elastic part;    -   the adhesive part is deposited on one of the first and second        elements and the elastic part is deposited on the other of said        first and second elements; and    -   the peelable film consists of a sprayable product.

According to a further aspect, the subject of the invention is also anelement, especially such as a motor vehicle door module, ready to befastened onto a frame or other surface, characterized in that theelement is provided with a composite sealing bead of defined shape anddefined cross section, said composite sealing bead having at least onecatching part suitable for cooperating with a surface or frame of saidelement, at least one elastic part and at least one adhesive part.

The composite sealing bead may fulfill a damping function with regard tosound, contributing to the soundproofing of the assembly, or with regardto shocks or stresses, by absorbing mechanical shocks or deformations.It may also accommodate the tolerances on the bodywork dimensions.

In one particular embodiment, the composite sealing bead has an elasticor viscoelastic part, which may be manufactured by a process in which aplastic is chemically foamed by means of a chemical agent (whether anadditive or a reactive function of the plastic itself that releases agas which expands the plastic, or by a process in which a plastic isphysically foamed by means of a gas mixed with the plastic in order toexpand the latter.

Another type of foaming or expansion consists in adding expanded orexpandable microspheres, for example of the EXPANCEL brand from AkzoNobel, or glass microspheres, for example of the ARMOSPHERES brand fromA.M.L. International or E-SPHERES from Envirospheres Pty Ltd.

Among materials that can be used to produce the elastic part, mentionmay be made by way of example of plasticized polyvinyl chloride,thermoplastic elastomers or polyurethanes, which may or may not bemodified by an elastomer, polyolefins or rubbers, especially butyl, EPDM(ethylene-propylene-diene), nitrile, styrene-butadiene, etc.

In general, thermoplastic elastomers (TPEs) consist of blends ofpolymers or of block copolymers manifesting a thermoplastic phase and anelastomeric phase possibly chemically bonded together in the case of acopolymer. An example of this is the product with the brand nameSANTOPRENE from AES, which consists of a polypropylene (PP)/EPDM blend,the EPDM being crosslinked in the form of nodules embedded in thecontinuous PP phase, with a variable PP weight ratio with respect to theEPDM. Also known are products based on block copolymer chains withelastomer blocks, especially isoprene or butadiene blocks, hydrogenatedor otherwise, which are linked to thermoplastic blocks, especiallypolystyrene blocks, for example the products with the brand name KRATONfrom Shell.

Also known are thermoplastic urethanes (TPUs) available in the form of anonreactive polymer obtained from several polyol sources, at least oneof which forms a block having thermoplastic properties and at least oneother forms a block having elastic properties. Examples are the productsPEARLTHANE or PEARLCOAT from Merquinsa, or ELASTOLLAN from Elastogran.

It is also possible to form the elastic part of the composite sealingbead based on polyurethane with a great variety of commerciallyavailable reactive compositions of the one-component or two-componenttype. As examples, mention may especially be made of one-componentcompositions based on a polyurethane prepolymer with a polyester,polyether, polycaprolactone, polyolefin or polysiloxane backbone. Aprepolymer with isocyanate end groups cures in the presence of moisturewith a certain foaming tendency; a prepolymer having siloxane end groupscures in the presence of moisture without foaming. These polyurethanecompositions may be modified by an elastomer, especially a nitrile, SBRor butyl rubber, or a thermoplastic elastomer or a polymer having acertain flexibility but which is not crosslinkable, such as polyolefinsor plasticized PVC. Examples of such compositions that can be used formanufacturing foamed or cellular materials, especially by the additionof a foaming gas, are described in EP-A-0 326 704 or EP-A-0 930 323.

The material of the elastic part of the composite sealing bead mayfurthermore contain organic or mineral fillers, such as talc, silica,calcium carbonate, alumina or metals.

The elastic part of the composite sealing bead has a density of lessthan 2.5, especially around 0.8 to 2.5 in the case of noncellularmaterials or 0.03 to 1 in the case of foamed or cellular materials.

The composite sealing bead also includes an adhesive part attached toone of the faces of the elastic part and intended to contribute to thebond between the first and second elements, in particular between a doormodule and a door of a motor vehicle. This adhesive part is in the formof a layer of adhesive and is chosen to remain inert during the storageperiod and to be optionally activated at the time of assembly.

In particular embodiments, the layer of adhesive consists of an adhesivewhich is thermally activatable, photoactivatable, chemicallyactivatable, repositionable, moisture-reactive and/or has a permanenttack. The same adhesive may have several of these properties combined.

When a repositionable adhesive is used, this is formulated so that, whenthe two elements are separated, a clear discontinuity appears, leavingone of the two elements unstained by any adhesive residue (this isuseful when disassembling the door, and allows the module to be reused).In contrast, when this adhesive is not repositionable, it is formulatedso that failure occurs within the elastic part, leaving a continuousdeposit of adhesive on each of the elements.

The layer of adhesive consists of an adhesive protected by a peelablefilm. As a variant, a a layer of adhesive is deposited on one of thefaces of the peelable film, which layer, by transfer and after removalof said film, is on the elastic part of the seal.

Thermal activation generally requires exposing the adhesive totemperatures exceeding room temperature in any season in temperateclimates; in general, it is unnecessary generally to provide aparticular protection for neutralizing the adhesive during the storageperiod. As a variant, it is also possible to use adhesives (especiallyepoxy-based adhesives) which have to be stored at very low temperatureso as to remain inert.

Likewise, an adhesive that can be activated by a defined chemicalreactant is generally not sensitive to the ambient atmosphere. Anadhesive that can be photoactivated by visible light may advantageouslybe protected from light by an opaque film. A moisture-reactive adhesivemust be protected by a moisture barrier film in order to be able to bestored for a long time. An adhesive having permanent tack must beprotected from any contact during its storage. In all cases, aprotective film, even if it is not obligatory, is desirable in order toprevent the surface of the adhesive being contaminated with dust whichcould hamper the final adhesive bonding.

As regards film, a plastic film may be used, especially a polyethylene,polyester, polyvinylchloride or polyvinylidene chloride or polyamidefilm, which may or may not be coated with a layer of silicone,especially fluorosilicone, in order in particular to protect asilicone-based adhesive layer. The film may also be reinforced by alayer of metal, especially aluminum, or it may consist of a composite.

Examples of thermally activated adhesives comprise resins of the epoxy,polyurethane, especially prepolymers having blocked or unblockedisocyanate end groups, polyether or polyester, especially polyacrylic,oxyalkylene or vinyl, and thermoplastics of polyolefin, especiallypolyethylene or polypropylene, or polyamide type. The layer of adhesivemay consist of a hot-melt adhesive, known hot-melt adhesives includingbutyl, especially styrene-butadiene rubbers, ethylene/vinyl acetatecopolymers (EVA), polyamides, polyaminoamides, or derived copolymers,polyesters and polyurethane-based compositions. The adhesive may containheat-activated crosslinking catalysts or curing additives.

Reactive or moisture-curing adhesives may be chosen from polyurethaneprepolymers having blocked or unblocked isocyanate end groups orsilane-terminated end groups, or silicones.

Chemically activatable adhesives may especially be the reactants curingby oxidation, or compositions containing an adhesive and an encapsulatedor heat-activatable curing catalyst.

Examples of adhesives having permanent tack consist especially ofacrylic polymers, elastomers, whether thermoplastic elastomers or not,polyolefins and polyurethanes, the permanent tack of which is providedor improved by the addition of tackifying resins and oils, or else bypolyurethanes formed from one or more diols or diamines anddiisocyanates in nonstoichiometric proportions.

As regards the use of the additive for forming said layer of adhesive,it is advantageous to use a hot-melt adhesive capable of being used inthe molten state, or a liquid adhesive or an adhesive in a liquidvehicle, especially as an organic solution or as an aqueoussuspension/dispersion which forms an adhesive layer by evaporation ofthe solvent vehicle or diluent.

As a variant, the adhesive may be sprayed and be in the form of a foam.

The adhesive is chosen to be compatible with the material of the elasticpart of the composite sealing bead, whether it can be envisaged to treatthe internal face of the layer of adhesive and/or the surface of theelastic part of the composite sealing bead with adhesion promoters orprimers, or even to interpose another adhesive between the elastic partof the composite sealing bead and the layer of adhesive.

The bonding of the layer of adhesive to the elastic part of thecomposite sealing bead may be reinforced by the fact that at least oneof the surfaces of the elastic part and of the layer of adhesive whichare in contact with each other is textured. The relief of the texturinghas the effect of increasing the area of contact between these two partsof the sealing bead and therefore of increasing the adhesion.

The composite sealing bead also includes a catching part intended tocontribute to the bond between the first and second elements, inparticular between the door module and the door of the motor vehicle.This catching part is located on one of the faces of the elastic part ofthe composite sealing bead, this face being, however, different fromthat which is coated with the aforementioned layer of adhesive. To takea nonlimiting example, this catching part is positioned symmetricallywith respect to the layer of adhesive deposited beforehand on theelastic part.

This catching part may be:

-   -   either in the form of one face of the elastic part, this face        then being intended to cooperate with a groove or the like        produced in one of the first and second elements, one region of        the elastic part is trapped within the groove and thus produces        a catching part;    -   or in the form of a layer of adhesive similar to the layer        already located on one of the other faces of the elastic part of        the composite sealing bead.

Whatever the embodiment of the catching part, this is intended tocooperate with one of the walls of one of the first and second elements.

The bond between the first and second elements is produced in thefollowing manner:

After the sealing bead according to the invention has been produced by amanufacturing process that will be explained in detail later, theadhesive part of the composite sealing bead is made to cooperate withone of the facing faces belonging to the first or second element, theelastic part of the composite sealing bead is mechanically stressed ordeformed (for example in compression, in extension or in shear), and thecatching part of the composite sealing bead is then brought up and thenfastened to another face of the facing assembly belonging to the otherelement. This fastening of the catching part is accomplished eithermechanically or using an adhesive layer.

The method according to the invention allows a composite sealing bead tobe shaped so as to reproduce a sealing pattern between two elements,advantageously when this pattern is a closed curve which especiallyfollows at least part of the periphery of the modular element. Themethod furthermore makes it possible to shape the cross section of thesealing bead so that it fits perfectly into the space that is reservedfor it in the final assembling operation, taking into account itsdeformability.

According to one embodiment, the composite sealing bead is formed on thefirst element or on the second element.

After having deposited, possibly using an extrusion process, a layer ofadhesive on one of the faces of said element and in the desired sealingpattern, a one-component or multicomponent product is then deposited,possibly by an extrusion process similar to the previous one, on thelayer of adhesive and in the same sealing pattern, this product havingto form the elastic part of the composite sealing bead. In the case of amulticomponent product, the seal may be formed, in an extrusion head, bythe reaction between at least two components fed separately into saidextrusion head.

When the elastic part of the composite sealing bead has been formed, andwhen it has reached its desired cross section and its mechanicalproperties, especially in terms of flexibility, surface finish andhardness, then has a bonding surface. This bonding surface is intendedto cooperate with a surface of the other modular element (the first orthe second element). The cooperation takes place either by adhesivebonding or by catching.

In the case of an adhesive bonding, the preformed composite sealing beadmay be provided with an adhesive surface as bonding surface on that sidewhere the modular element is presented, or else it is the modularelement itself which has an adhesive surface—the modular elementpossibly adhering to the bead because it (or at least part of it) isformed in contact with the composite bead from a substance adhering tothe latter.

According to another embodiment, different from the previousembodiments, the composite sealing bead may be formed by depositing thelayer of adhesive in a mold cavity and by molding the elastic part ofthe composite sealing bead in the mold cavity by depositing a suitablemoldable product on the layer of adhesive in the mold cavity.

Depending on the way in which the modular element used is obtained, itis then possible:

-   -   either to form the composite sealing bead as a single piece with        one of the modular elements; the modular element (or at least        one portion of the latter) can therefore be molded directly on        the layer of adhesive so as simultaneously to produce the        modular element (or the modular element portion) and the        composite sealing bead;    -   or to form the bead from the modular element separately; it is        possible either to transfer the composite bead to a        prefabricated modular element or to mold the modular element in        contact with the sealing bead in said cavity. The sealing bead        can then be cured in the mold and/or after the composite sealing        bead has been transferred to the modular element.

The moldable material may be deposited in a closed mold by injecting aliquid. A process may also be carried out in a mold cavity by extrusion(or another suitable delivery method) of a viscous or pasty material,with the aid of movable delivery means, the mold being stationary, orelse stationary delivery means, the mold then being movable.

The molding technique also applies to the production of the adhesivepart of the composite sealing bead, reproducing the bonding pattern,this adhesive part of the sealing bead being protected or activatable onone face and having a surface for bonding to the modular element. Theadhesive part may be obtained in a mold cavity, possibly containing aprotective film, by injection molding or by extrusion of a viscousmaterial in the cavity.

If the adhesive part of the composite sealing bead is protected by apeelable film, the moldable adhesive material is chosen from those inwhich the modulus of elasticity in the uncrosslinked state is sufficientto allow the film to be peeled off without tearing the elastic part ofthe sealing bead.

Such materials comprise, in particular, moisture-crosslinkable systemsthat can be protected by a moisture barrier film, especially systems ofthe one-component, preferably thermoplastic, polyurethane type, possiblymodified by an elastomer. Such a system is a polyurethane prepolymerhaving a backbone of the polyester, polyether or polyolefin type,obtained for example from a polyol and a polyisocyanate, at least one ofwhich has a polymeric or oligomeric backbone as mentioned above.

As a variant, the composite sealing bead may be formed by depositing thepreformed, especially premolded, elastic part of the sealing bead on thelayer of adhesive in the mold cavity, the superposition of the two partsin another mold allowing the precise shape of the sealing bead to becontrolled. In this variant, the preformed elastic part of the sealingbead may be an integral part of a modular element (or a portion of thelatter) manufactured by molding.

In both cases, the layer of adhesive may be deposited in the mold in theform of a preformed strip or of reactive, liquid or viscous material.The adhesive may also be provided with the elastic part of the seal bycoextrusion or by spraying.

Preferably, a peelable protective film is applied beforehand to thesurface of the mold cavity as mold release agent. This peelable film mayconstitute the protection for the adhesive part. In particular, the filmmay have moisture barrier properties in order to protect a layer ofmoisture-reactive adhesive.

When applying a composite sealing bead which has been producedseparately for which the catching part of the latter consists of a layerof adhesive, this adhesive may be placed between the composite sealingbead and the modular element. This adhesive may be identical to ordifferent than that already used to form the adhesive part of thecomposite sealing bead.

Such a composite sealing bead may be manufactured especially bycoextruding the adhesive on at least one of the faces of the elasticpart of the composite sealing bead, it being possible for thecoextrusion product to be deposited in a mold cavity preequipped with aprotective film, in order to assume its final shape. The term“coextrusion” is understood here to mean both the formation of theelastic part and of at least one adhesive part the sealing beadsimultaneously with its deposition by means of an extrusion head fedwith at least two extrudable materials, and the application of at leastone adhesive material in an extrusion head through which the elasticpart of the preformed sealing bead, especially one preformed byextrusion, passes.

In another embodiment, the material of the elastic part of the compositesealing bead is itself chosen to be adhesive and to bond to the modularelement in the uncured or partially cured state or after activation,especially thermal activation.

One manufacturing process consists in depositing, for example in a moldcavity preequipped with a protective film, a layer of adhesive and thena moldable material forming the elastic part of the composite sealingbead (this elastic part possibly being covered with a layer ofadhesive), and then in pressing either of the first and second elementsagainst the elastic part of the sealing bead in order to bond thesealing bead to said modular element. Next, the elastic part of thecomposite sealing bead may possibly be at least partly cured in thismold thus closed by the modular element, before said modular element towhich the composite sealing bead is fastened, including as the case maybe its protective film, is removed. The curing of the composite sealingbead may be carried out or completed outside the mold by cooling or byreaction with the moisture of the air.

The method according to the invention allows the mass production ofmodular elements ready to be assembled, this manufacture possibly beingautomated. The final assembly of these modular elements is very rapidand meets the need to reduce the assembly time for assemblies such asmotor vehicles.

Further details and advantageous features will become apparent below onreading the description of illustrative, but nonlimiting, examples ofthe invention, with reference to the appended drawings in which:

FIG. 1 shows a perspective view of a door module being assembled on anautomobile door;

FIG. 2 shows a sectional view of the border region of the door moduleequipped with a composite sealing bead according to a first embodiment;

FIG. 3 shows a sectional view of the border region of the door moduleequipped with a composite sealing bead according to a second embodiment;

FIG. 4 illustrates the manufacture of the composite sealing bead bytransfer;

FIG. 5 illustrates the manufacture of the composite sealing bead bydirect extrusion on one of the elements; and

FIG. 6 shows a sectional view of the border region of the door moduleequipped with a composite sealing bead according to a third embodiment.

It should firstly be pointed out that for the sake of clarity therelative proportions between the various elements shown have not beenrespected.

FIG. 1 shows a perspective view of a first element, especially a door 1of a motor vehicle equipped with a second element, especially a doormodule 2 attached to a surface 3 or frame belonging to said door 1.

The door module 2 is shown in the nonassembled position, in order toreveal its face turned toward the surface 3 of the door 1 of thevehicle. To simplify examination of the figure, no accessory orequipment has been shown on the door module, but it goes without sayingthat all the usual equipment items, such as a pocket, etc., may beintegrated into this module.

The door module 2 is mounted on the surface 3 of the door 1 byinterposing, between the internal face of the door module 2 and thesurface 3 of the door 1, a composite sealing bead 4. In this case, thesealing pattern is in the form of a closed frame bearing along theperiphery of the door module. The sealing bead 4 must ensure that thereis a seal between the door module 2 and the door 1 and can also fulfillother functions, such as the absorption of vibrations between theinternal space and the external space that are bounded by these twoparts, as well as the fastening between the two elements.

The structure of the sealing bead 4 is a composite structure accordingto the invention and can be seen in FIG. 2, which also shows thestructure of the module 2. In this figure, the module is shown as it isbefore being mounted on the vehicle.

The composite sealing bead 4 is formed from an elastic part 5 bonded toone of the first or second elements and from an adhesive part 6 fastenedto the elastic part of the sealing bead and protected by a film 7.

A preferred composition for the flexible part 5 is the following (allthe proportions being expressed in % by weight):

-   -   polyol: LUPRANOL 2043 sold by BASF: 81.0%;    -   water: 0.8%;    -   isocyanate: SUPRASSEC X2647 sold by Huntsman: 17.0%; and    -   catalyst: TOYOCAT B41 sold by Tosoh: 1.2%.

The bonding between the elastic part 5 of the sealing bead 4 and one ofthe elements may be achieved by means of a second adhesive part 8 (FIG.2) or by means of a catching part 9 (FIG. 3).

The sealing bead 4 has a calibrated cross section according to thepermitted separation between the first and second elements. In thiscase, the cross section is shown as being approximately square, but itmay be of any other cross section. To fulfill the sealing function, andto compensate for the manufacturing tolerances on the bodywork, theelastic part 5 of the sealing bead 4 is made of a viscoelastic material.

On the opposite side of the door module, the sealing bead 4 is providedwith an adhesive layer 6 at least partly covering the surface of thebead.

As small an amount of adhesive as possible is used to ensure effectivebonding, whereas the elastic part 5 of the sealing bead 4 occupies atleast about 50% of the volume of the sealing bead 4. A preferredadhesive material is an adhesive with permanent tack or else amoisture-curing polyurethane. In general, the purpose of the film 7 isto prevent, during the storage period on the premises of the modulemanufacturer or of the automobile manufacturer, dust from contaminatingthe sealing bead and to prevent any contact with a surface other thanthe final assembly surface which could damage the layer of adhesive 6.The function of the film is also to protect the layer of adhesive fromthe external conditions, especially moisture, light and oxygen, liableto prematurely activate the adhesive 6.

The manufacture of the composite sealing bead is illustrated in FIG. 4.Placed in the cavity 10 of a mold 11 is a film 7 whose face in contactwith the mold (which will be the external face of the film once the bead4 has been completed) may be made of polyethylene in order to act as arelease agent for the molded material. According to a variant, not shownin the figures, the film is deposited by spraying. Deposited on theinternal face of the film 7 is a layer of adhesive 6 in the form of astrip that can be unreeled or else in the form of a fluid or viscousmaterial, especially a hot-melt adhesive in the molten state or a liquidadhesive or an adhesive in the form of an organic solution or aqueousdispersion, the solvent or diluent of which is evaporated, which layerof adhesive is shaped in the cavity. Next, the material of the elasticpart 5 of the sealing bead is deposited on the layer of adhesive 6, forexample by means of an extrusion nozzle 12 which is moved along theentire length of the cavity 10 in a closed circuit (it is also possiblefor the extrusion nozzle 12 to remain stationary and for the mold tomove relative to the nozzle). In this way, it is possible to form a beadin the shape of a frame without any discontinuity and thereforeresulting in no loss of sealing. The nozzle 12 may have a calibratedcross section in order to give a preliminary shape to the material ofthe elastic part 5 of the bead 4, which ends up being shaped in thecavity 10 of the mold 11.

As soon as the material of the elastic part 5 of the sealing bead 4 hasbeen deposited, the composite sealing bead may be fitted onto the doormodule, by transferring it onto the latter: the door module 2, depictedby the dot-dashed line, is pressed (in the direction of the arrows F)against the surface 13 of the not yet cured bead 4 and the materialadheres spontaneously to the surface of the module. As a variant, anadditional layer of adhesive, which may or may not be identical to thatof the layer 6, may be applied to the surface 13 of the elastic part 5of the cured or uncured sealing bead 4 (if the material of the bead 4does not adhere spontaneously to the material of the module 2). It isthis second layer that then forms the adhesive surface 13 of the bead 4.

After an application time varying in length depending on the materialsemployed, the door module 2 can be removed from the surface of the moldwith the composite bead 4 bonded to its surface. The film 7 is alsoextracted from the mold cavity and remains attached to the layer ofadhesive 6 that it immediately protects from dust and/or moisture.

The module 2 thus equipped with the bonding bead 4 may be held for atime long enough for the bead 4 to cure or for it to acquire thestructural properties, and then stored awaiting its use for mounting ona vehicle.

Mounting takes place simply by removing the protective film 7, afterwhich the bead 4 is pressed into contact with the door of the motorvehicle. With a thermally activatable adhesive, the layer of adhesivemay firstly be heated, especially by an infrared source, or else themodule 2 may be put into place against the door, followed by heating toraise the bonding bead to the temperature needed to activated theadhesive, for example by heating the door.

FIG. 6 shows an alternative embodiment of the composite sealing bead 4,in which the surface of the layer of adhesive 6 which bonds to theelastic part 5 of the sealing bead is textured so as to increase thearea of contact between these two parts of the composite sealing bead.Such a layer of adhesive 6 may especially be produced by depositing anadhesive material in the cavity 10 using a nozzle 12 of appropriatecross section. The elastic part 5 of the composite sealing bead 4 isthen preferably obtained by extruding a viscous or pasty material ontothe textured surface of the layer of adhesive 6. The extruded materialof the elastic part 5 of the sealing bead 4 follows the contour of thetextured face of the layer 6 over a contact area greater than that witha flat contact, hence resulting in better adhesion.

FIG. 5 illustrates another aspect of the invention in which thecomposite sealing bead 4 is formed directly on the first element or thesecond element.

After having deposited, possibly using an extrusion process, a layer ofadhesive 8 on one of the faces of said element and in the desiredsealing pattern, a one-component or multicomponent product is thendeposited, possibly by an extrusion process similar to the previous one,on the layer of adhesive 8 or simply on the catching part 9, and in thesame sealing pattern, this product having to form the elastic part 5 ofthe composite sealing bead 4. In the case of a multicomponent product,the seal 4 may be formed, in an extrusion head, by the reaction betweenat least two components fed separately into said extrusion head.

The door module 2 has a structure identical to that of the module inFIGS. 2, 3 and 6. It is provided with an elastic part 5 placed aroundthe periphery of the module on or beside the lining.

The elastic part 5 is bonded on a first face to the module 2 and isprotected on the other face by a film 7, the protected face beingadhesive after the film has been removed.

For this purpose, the elastic part 5 of the bead 4 may be covered with amoisture-crosslinkable adhesive, the film 7 having a moisture barrierfunction, for example made of low-density polyethylene. The adhesivematerial that can be used may be chosen from among systems based onpolyurethane, advantageously thermoplastic polyurethane, optionallymodified by at a polymer, especially an elastomer, in order to give theadhesive the desired mechanical properties. Most particularly preferredamong these materials are polyurethane prepolymers having a polymeric oroligomeric, especially polyether and/or polyester, backbone. Amoisture-crosslinkable thermoplastic polyurethane composition suitablefor this use may be obtained by the hot reaction of 2 parts of apolyester diol sold under the brand name DYNACOLL® 7231 by Degussa-Hulswith 1 part of a polyether-based isocyanate prepolymer sold under thebrand name LUPRANAT® MP130 by BASF.

The elastic part 5 of the sealing bead 4 is manufactured in a mannervery similar to that described above with reference to FIG. 4, except asregards the deposition phase which is carried out directly on thesurface of one of the first or second elements, without passing via atransfer mold.

Moreover, the bead may be applied to the second element (or to the firstelement) by pressing the first element (or the second element) bypressing on the first element (or the second element), the sealing beadstill having an adhesive upper face for bonding to said (first orsecond) element, the material of the core of the sealing bead possiblybeing cured or set by keeping the first and second elements clampedagainst each other.

In another alternative embodiment, the adhesive may be chosen fromthermally activatable materials, especially hot-melt adhesives, orchemically activatable materials. It is no longer essential in this caseto provide the protective film 7, although this is still preferred inorder to protect the activatable surface from any dust or dirt liable tocounteract the activation and/or adhesion of the activated face.

The invention has been described in the particular case of themanufacture of a door module ready to be mounted on a door frame of amotor vehicle, but it applies to the production of any other modularelement, especially window modules that can be used in the automobileindustry or in the construction of buildings (conservatories, porches,etc.).

1-21. (canceled)
 22. A method of producing a composite sealing bead between a first element and a second element, comprising: providing one element chosen from the first and second elements with a composite sealing bead of defined shape and defined cross section, the composite sealing bead having at least one catching part, configured to cooperate with the element chosen from the first and second elements, having at least one elastic part, presenting on its peripheral surface, a skin forming an impermeable covering, and having at least one adhesive part configured to cooperate with the other non-chosen of the first and second elements when the first and second elements are to be fitted together.
 23. The method as claimed in claim 22, wherein the composite sealing bead is deposited beforehand in a transfer mold before the sealing bead is applied to either of the first and second elements.
 24. The method as claimed in claim 22, wherein the composite sealing bead is deposited directly on either of the first and second elements.
 25. The method as claimed in claim 22, wherein the composite sealing bead is deposited by at least one extrusion operation.
 26. The method as claimed in claim 22, wherein the composite sealing bead is formed by extruding a one-component product.
 27. The method as claimed in claim 22, wherein the composite sealing bead is formed in an extrusion head by reaction between at least two components brought separately into the extrusion head.
 28. The method as claimed in claim 22, wherein the elastic part of the composite sealing bead comprises a foamed material.
 29. The method as claimed in claim 22, wherein the elastic part is based on a thermoplastic elastomer or on a polyurethane that may or may not be modified by an elastomer.
 30. The method as claimed in claim 22, wherein the elastic part represents at least 50% by volume of the composite sealing bead.
 31. The method as claimed in claim 22, wherein the adhesive part of the composite sealing bead includes a repositionable thermally activatable, photoactivatable, chemically activatable adhesive.
 32. The method as claimed in claim 22, wherein the adhesive part of the composite sealing bead includes an adhesive that has a permanent tack or is moisture-reactive, protected by a peelable film.
 33. The method as claimed in claim 32, wherein the adhesive part is formed with the peelable film and is deposited by transfer onto the elastic part of the composite sealing bead during removal of the peelable film.
 34. The method as claimed in claim 22, wherein the adhesive part of the composite sealing bead includes a hot-melt adhesive or is formed from a liquid adhesive or an adhesive in a liquid vehicle.
 35. The method as claimed in claim 22, wherein the adhesive part of the composite sealing bead includes a sprayable adhesive.
 36. The method as claimed in claim 22, wherein the adhesive part and the elastic part of the composite sealing bead are formed from an identical product.
 37. The method as claimed in claim 22, wherein the catching part of the composite sealing bead includes another adhesive part.
 38. The method as claimed in claim 22, wherein the adhesive part is coextruded with the elastic part.
 39. The process as claimed in claim 22, wherein the adhesive part is deposited on one of the first and second elements and the elastic part is deposited on the other of the first and second elements.
 40. The method as claimed in claim 32, wherein the peelable film includes a sprayable product.
 41. An element, ready to be fastened onto a frame or other surface, wherein the element is provided with a composite sealing bead of defined shape and defined cross section, the composite sealing bead having at least one catching part configured to cooperate with a surface or frame of the element, at least one elastic part, and at least one adhesive part. 